WO2023063807A1 - Polarizing plate and use thereof - Google Patents

Abstract

The present application relates to a polarizing plate and use thereof. The present application provides a polarizing plate and an OLED display device comprising same, the polarizing plate alleviating the problem of the rainbow effect occurring on the exterior of the OLED display device and offering excellent visual sensation, excellent hardness, and excellent durability against heat and moist heat.

Description

Polarizer and its use

This application relates to a polarizing plate and its use.

This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0137842 dated October 15, 2021 and Korean Patent Application No. 10-2022-0080539 dated June 30, 2022, and the All material disclosed in the literature is incorporated as part of this specification.

In order to improve the luminance of organic light emitting diode (OLED) display devices, various methods for improving the performance of OLED display panels have been attempted. However, when the luminance of the OLED display panel increases, the rainbow stain phenomenon, which has not previously occurred, is intensified, and due to the stain phenomenon, the appearance of the OLED display device may deteriorate (Patent Document 1: Republic of Korea Patent Publication No. 10- 2009-0122138).

The present application provides a polarizing plate capable of improving the problem of occurrence of rainbow stains on the appearance of an OLED display device, excellent visual sensation, excellent hardness, and excellent heat and moisture resistance durability, and an OLED display device including the polarizing plate.

This application relates to a polarizing plate. The polarizing plate may include a polarizer and a scattering adhesive layer present on one surface of the polarizer.

In the present specification, the pressure-sensitive adhesive layer may be, for example, a layer of a pressure-sensitive adhesive composition. In this specification, the term "layer of a pressure-sensitive adhesive or adhesive composition" may mean a layer formed by coating or curing a pressure-sensitive adhesive or adhesive composition. The term "curing of the pressure-sensitive adhesive or adhesive composition" may mean implementing a cross-linked structure in the pressure-sensitive adhesive or adhesive composition through physical or chemical action or reaction of components included in the pressure-sensitive adhesive or adhesive composition. Curing can be induced, for example, by holding at room temperature, applying moisture, applying heat, irradiating active energy rays, or by proceeding two or more of the above processes together, and depending on each case, the type of curing is induced. The pressure-sensitive adhesive or adhesive composition may be referred to as, for example, a room temperature-curable pressure-sensitive adhesive or adhesive composition, a moisture-curable pressure-sensitive adhesive or adhesive composition, a heat-curable pressure-sensitive adhesive or adhesive composition, an active energy ray-curable pressure-sensitive adhesive or adhesive composition, or a hybrid curing pressure-sensitive adhesive or adhesive composition. there is.

In the present specification, the scattering pressure-sensitive adhesive layer may refer to a pressure-sensitive adhesive layer containing scattering particles that may cause haze in the pressure-sensitive adhesive layer. The scattering particles may be, for example, beads described later.

The polarizing plate including the scattering pressure-sensitive adhesive layer may have a haze of 15% or more. The haze does not mean the haze of the scattering pressure-sensitive adhesive layer itself, and may mean the haze of the polarizing plate including the scattering pressure-sensitive adhesive layer and the polarizer. As described later, when the polarizing plate further includes functional layers such as a protective film, a retardation layer, and a hard layer, it may mean a haze of a scattering adhesive layer, a polarizer, and a polarizing plate including the functional layers. The haze is specifically, 15% or more, 16% or more, 17% or more, 18% or more, 19% or more, 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, 25 or more, 26 % or more, 27% or more, 28% or more, 29% or more, 30% or more, 31% or more, 32% or more, 33% or more, 34% or more, 35% or more, 36% or more, 37% or more, 38% or more , 39% or more or 40% or more, 50% or less, 48% or less, 46% or less, 44% or less, 42% or less, 40% or less, 38% or less, 36% or less, 34% or less, 32% or less , 30% or less, 28% or less, 26% or less, 24% or less, 22% or less or 20% or less. The haze of the polarizing plate may be a value measured based on a D65 light source. The haze of the polarizer may be a value measured for light having a wavelength of about 380 nm to about 780 nm. The haze may be an average haze value measured for light having a wavelength of about 380 nm to about 780 nm. When the haze of the polarizing plate is within the above range, it may be advantageous to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance.

The scattering pressure-sensitive adhesive layer may have a storage modulus of 70,000 Pa or more at a temperature of 25° C. and a frequency of 1 rad/sec. The storage modulus is specifically 72,000 Pa or more, 74,000 Pa or more, 76,000 Pa or more, 78,000 Pa or more, 80,000 Pa or more, 81,000 Pa or more, 82,000 Pa or more, 83,000 Pa or more, 84,000 Pa or more, 85,000 Pa or more, 86,000 Pa or more, 87,000 Pa or more, 88,000 Pa or more or 89,000 Pa or more. The upper limit of the storage modulus may be, for example, 100,000 Pa or less, 95,000 Pa or less, or 90,000 Pa or less. When the storage modulus of the scattering pressure-sensitive adhesive layer is within the above range, it is possible to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and it may be advantageous to exhibit excellent visual sensation, excellent hardness, excellent heat resistance and moist heat resistance.

The scattering adhesive layer may include an adhesive resin. In one example, the adhesive resin may be an acrylic resin. The acrylic resin may be a polymer that includes an acrylic monomer as a main component and exhibits tackiness before or after crosslinking. In the present specification, to include an acrylic monomer as a main component means to include 80 wt% or more, 85 wt% or more, 90 wt% or more, 95 wt% or more, or 99 wt% or more of an acrylic monomer among all monomers constituting the adhesive resin. can mean

In one example, the adhesive resin may be an acrylic polymer including polymerized units derived from (meth)acrylic acid ester monomers. In this specification, the term "monomer" refers to all kinds of compounds capable of forming polymers through a polymerization reaction, and a polymer including a polymerized unit derived from a certain monomer means a polymer formed by polymerization of the certain monomer. can

As the (meth)acrylic acid ester compound, for example, alkyl (meth)acrylates can be used. The alkyl (meth)acrylate includes, for example, 1 to 20 carbon atoms, 1 to 14 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 carbon atom, in consideration of cohesion, glass transition temperature, and adhesiveness control. An alkyl (meth)acrylate having an alkyl group of 4 to 4 may be used. In the above, the alkyl group may be, for example, a straight-chain alkyl group, a branched-chain alkyl group, or a cyclic alkyl group. Examples of such monomers are methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-methyl hepyl acrylate, pentyl acrylate, 2-ethyl Hexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, isobornyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate and lauryl (meth)acrylate. One or more of the above may be appropriately selected and used.

The acrylic polymer may further include a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group (hereinafter, simply referred to as a crosslinkable monomer). In the present specification, the copolymerizable monomer having a crosslinkable functional group has a site that can be copolymerized with other monomers included in the polymer, such as the (meth)acrylic acid ester monomer, and also has a crosslinkable functional group to crosslink the polymer. It may mean a compound capable of imparting a sexual functional group. The crosslinkable functional group may be, for example, a carboxyl group. In one example, the crosslinkable monomer may be acrylic acid. The acrylic polymer may not include (meth)acrylate having a hydroxyl group as a crosslinkable monomer.

In one example, the acrylic polymer may include a polymerization unit derived from 80 parts by weight to 99 parts by weight of the (meth)acrylic acid ester monomer and 1 part by weight to 20 parts by weight of the crosslinkable monomer. In another example, the acrylic polymer may include a polymerization unit derived from 90 parts by weight to 99 parts by weight of the (meth)acrylic acid ester monomer and 1 part by weight to 10 parts by weight of the crosslinkable monomer. Within this range, the pressure-sensitive adhesive layer may implement an appropriate cross-linked structure.

If necessary, the acrylic polymer may further include other optional comonomers, for example, to adjust appropriate physical properties. Examples of the comonomer include alkoxyalkylene glycol (meth)acrylic acid ester, alkoxy dialkylene glycol (meth)acrylic acid ester, alkoxy trialkylene glycol (meth)acrylic acid ester, alkoxy tetraalkylene glycol (meth)acrylic acid ester, alkoxy Polyethylene glycol (meth)acrylic acid ester, phenoxyalkylene glycol (meth)acrylic acid ester, phenoxy dialkylene glycol (meth)acrylic acid ester, phenoxy trialkylene glycol (meth)acrylic acid ester, phenoxy tetraalkylene glycol ( alkylene oxide group-containing monomers such as meth)acrylic acid ester or phenoxy polyalkylene glycol (meth)acrylic acid ester; styrenic monomers such as styrene or methyl styrene; glycidyl group-containing monomers such as glycidyl (meth)acrylate; or carboxylic acid vinyl esters such as vinyl acetate, but is not limited thereto. These comonomers may be included in the polymer by selecting one or more types of appropriate comonomers as needed. Such a comonomer may be included in the polymer in an amount of, for example, 20 parts by weight or less, or 0.1 part by weight to 15 parts by weight based on the total weight of other compounds used as polymerized units in the polymer.

Acrylic polymer is a mixture of monomers obtained by selecting necessary monomers from among the above-described monomers and blending the selected monomers in a desired ratio through solution polymerization, photo polymerization, bulk polymerization, or suspension polymerization. It can be manufactured by applying a polymerization method such as suspension polymerization or emulsion polymerization.

The pressure-sensitive adhesive layer may further include a multifunctional crosslinking agent (curing agent). The multifunctional crosslinking agent may react with the acrylic polymer to realize a crosslinked structure. In the present specification, the multifunctional crosslinking agent may mean a crosslinking agent including two or more crosslinkable functional groups.

The type of specific crosslinking agent that can be used in the present application is not particularly limited, and may be selected in consideration of the type of crosslinkable functional group included in the acrylic polymer. As the crosslinking agent, general crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents and metal chelate crosslinking agents can be used. For example, an isocyanate crosslinking agent may be used, but is not limited thereto. Specific examples of the isocyanate crosslinking agent include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, and any one of the above polyols (ex. trimethylol propane) and at least one selected from the group consisting of reactants; Specific examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine and glycerin diglycidyl ether. and one or more selected from the group consisting of; Specific examples of the aziridine crosslinking agent include N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), copymid), triethylene melamine, bisisoprotaloyl-1-(2-methylaziridine), and at least one selected from the group consisting of tri-1-aziridinylphosphine oxide, but is not limited thereto no. In addition, as specific examples of the metal chelate crosslinking agent, compounds in which a multivalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium and/or vanadium are coordinated with acetyl acetone or ethyl acetoacetate, etc. , but is not limited thereto.

The crosslinking agent may be included in an amount of 0.01 to 10 parts by weight or 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic polymer. If the content of the crosslinking agent is less than 0.01 parts by weight, the cohesive strength of the pressure-sensitive adhesive layer may deteriorate, and if it exceeds 10 parts by weight, durability reliability may deteriorate, such as peeling between layers or lifting.

The scattering pressure-sensitive adhesive layer may have a cross-linked structure formed by a cross-linking reaction between the acrylic polymer and the multifunctional cross-linking agent. The pressure-sensitive adhesive layer may not have a cross-linked structure formed by a polymerization reaction of a radically polymerizable compound. Accordingly, the pressure-sensitive adhesive layer may not include a polymerization initiator.

The scattering adhesive layer, if necessary, in addition to the above-mentioned components, a known antistatic agent, a silane coupling agent, a tackiness imparting resin, an epoxy resin, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer may further include one or more additives selected from the group consisting of

The scattering adhesive layer may further include beads. The storage modulus of the scattering pressure-sensitive adhesive layer and the haze of the polarizing plate may refer to the storage modulus of the pressure-sensitive adhesive layer including beads and the haze of the polarizing plate. The refractive index of the bead may be different from the refractive index of the adhesive resin. By including beads in the pressure-sensitive adhesive layer, haze can be imparted to the pressure-sensitive adhesive layer to improve visibility of rainbow spots that may occur during manufacturing of the OLED display device.

In one example, the difference (AB) between the refractive index (A) of the adhesive resin and the refractive index (B) of the bead may be 0.04 or more. Since the greater the difference in refractive index between the adhesive resin and the bead is, it is relatively more advantageous to implement a haze, so a high haze can be implemented even with a small amount. An upper limit of the refractive index difference (A-B) may be, for example, 0.1 or less. The refractive index is a value measured for a light source having a wavelength of 350 nm to 1450 nm at a temperature of 25° C. using an Abbe refractometer. If the difference in refractive index is too small, it is difficult to express the haze at the desired level, and if the difference in refractive index is too large, optical properties may be deteriorated due to loss of light traveling straight, so it is appropriate that the difference in refractive index is within the above range. . In one example, the refractive index of the bead may be within the range of 1.415 to 1.425.

The content of beads may be appropriately selected within a range not impairing the purpose of the present application. In one example, the beads may be included in the range of 1 part by weight to 3 parts by weight when the weight of all components of the scattering pressure-sensitive adhesive layer is 100 parts by weight. In the present specification, the weight of all components of the scattering pressure-sensitive adhesive layer may mean the sum of weights of all adhesive resins, crosslinking agents, additives, and beads included in the scattering pressure-sensitive adhesive. Alternatively, in the present specification, the weight of all components of the scattering pressure-sensitive adhesive layer may mean the sum of the weights of all components except for the solvent in the pressure-sensitive adhesive composition. More specifically, the beads may be included in an amount of 1 part by weight or more, 1.2 parts by weight or more, 1.4 parts by weight or more, 1.5 parts by weight or more, 1.6 parts by weight or more, or 1.8 parts by weight or more based on 100 parts by weight of all components of the scattering pressure-sensitive adhesive layer, 3 parts by weight or less, 2.8 parts by weight or less, 2.6 parts by weight or less, 2.4 parts by weight or less, or 2.2 parts by weight or less. In another example, beads may be included in an amount of 2 parts by weight or more based on 100 parts by weight of the adhesive resin. Specifically, the amount of beads is 2.2 parts by weight or more, 2.4 parts by weight or more, 2.6 parts by weight or more, 2.8 parts by weight or more, 3.0 parts by weight or more, 3.2 parts by weight or more, 3.4 parts by weight or more, 3.6 parts by weight or more based on 100 parts by weight of the adhesive resin. 3.8 parts by weight or more, 4.0 parts by weight or more, 4.2 parts by weight or more, 4.4 parts by weight or more, 4.6 parts by weight or more, 4.8 parts by weight or more, 5.0 parts by weight or more, 5.2 parts by weight or more, 5.4 parts by weight or more, 5.6 parts by weight or more or more, 5.8 parts by weight or more, 6.0 parts by weight or more, 6.5 parts by weight or more, 7.0 parts by weight or more, 7.5 parts by weight or more or 8.0 parts by weight or more, 10 parts by weight or less, 9.5 parts by weight or less, 9 parts by weight or less , 8.5 parts by weight or less, 8 parts by weight or less, 7.5 parts by weight or less, 7 parts by weight or less, 6.5 parts by weight or less, 6 parts by weight or less, 5.5 parts by weight or less, 5 parts by weight or less, 4.5 parts by weight or less, 4 parts by weight or less , 3.5 parts by weight, 3.0 parts by weight or less, 2.5 parts by weight or less, or 2.0 parts by weight or less may be included. When the content of the beads is within the above range, it may be advantageous to improve the problem of rainbow stains occurring on the exterior of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance. On the other hand, if the content of the beads is too large, it may be advantageous that the content of the beads is within the above range because the camera recognizes the beads during the attachment process and catches the reference line incorrectly, resulting in an attachment error.

In one example, the beads may be organic beads. The organic beads may include, for example, silicone resin. The silicone resin may include, for example, silsesquioxane. The silsesquioxane may be a compound having a chemical formula of [RSiO _3/2 ]n, and R = H, alkyl, aryl or alkoxy. In one example, the silicone resin may be polymethylsilsesquioxane.

In one example, the beads may be spherical particles. The size of the beads may be appropriately selected within a range not impairing the purpose of the present application. In one example, the average particle diameter (D50) of the beads may be 6 μm or less. The average particle diameter (D50) of the beads is specifically, 5.8 μm or less, 5.6 μm or less, 5.4 μm or less, 5.2 μm or less, 5.0 μm or less, 4.8 μm or less, 4.6 μm or less, 4.4 μm or less, 4.2 μm or less, 4.0 μm or less or less, 3.8 μm or less, 3.6 μm or less, 3.4 μm or less, 3.2 μm or less, 3.0 μm or less, 2.9 μm or less, 2.8 μm or less, 2.7 μm or less, 2.6 μm or less, or 2.5 μm or less. The average particle diameter (D50) of the beads may be, for example, 1 μm or more, 1.5 μm or more, 2.0 μm or more, or 2.2 μm or more. When the average particle diameter of the beads is within the above range, it may be advantageous to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance. On the other hand, in terms of preventing a sparkling phenomenon and/or camera recognition error during the attachment process, the average particle diameter (D50) of the beads may be 3 μm or less, 2.5 μm or less, or 2.0 μm or less.

The thickness of the scattering adhesive layer may be within a range of 15 μm to 25 μm. Specifically, the thickness of the scattering adhesive layer may be 16 μm or more, 17 μm or more, or 18 μm or more, and may be 24 μm or less, 23 μm or less, or 22 μm or less. When the thickness of the scattering pressure-sensitive adhesive layer is within the above range, it may be advantageous to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance.

In one example, the scattering pressure-sensitive adhesive layer may have a glass sliding distance of 250 μm or less measured at 800 gf for 1000 seconds. In this specification, the glass sliding distance may mean the sliding distance of the scattering adhesive layer with respect to the glass plate. The sliding distance of the scattering adhesive layer may be a value measured after attaching the polarizing plate so that the scattering adhesive layer touches the glass plate. Specifically, the glass sliding distance may be 240 μm or less, 230 μm or less, 220 μm or less, or 210 μm or less. The lower the glass slip distance, the higher the hardness of the sample. Since the beads do not chemically react with the pressure-sensitive adhesive itself, there is a possibility of affecting the hardness of the pressure-sensitive adhesive layer, and if a decrease in hardness occurs, the reliability of the pressure-sensitive adhesive layer may be affected. When the hardness of the pressure-sensitive adhesive layer is high, there is an advantage in that deformation of the pressure-sensitive adhesive layer is minimized because resistance to external deformation is high. The lower limit of the glass sliding distance may be, for example, 150 μm or more, 160 μm or more, 170 μm or more, 180 μm or more, 190 μm or more, or 200 μm or more. When the glass sliding distance of the scattering pressure-sensitive adhesive layer is within the above range, it may be advantageous to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance.

In this specification, the term "polarizer" means a film, sheet, or device having a polarizing function. A polarizer is a functional element capable of extracting light vibrating in one direction from incident light vibrating in several directions.

The polarizer may be an absorption type polarizer. In this specification, an absorption type polarizer refers to an element that exhibits selective transmission and absorption characteristics with respect to incident light. The absorption type polarizer may transmit light vibrating in one direction from incident light vibrating in various directions and absorb light vibrating in the other direction.

The polarizer may be a linear polarizer. In this specification, a linear polarizer means a polarizer in which light selectively transmitted is linearly polarized light oscillating in one direction and light selectively absorbed is linearly polarized light oscillating in a direction orthogonal to the oscillation direction of the linearly polarized light.

As the polarizer, for example, a polarizer in which iodine is dyed on a polymer stretched film such as a PVA stretched film, or a liquid crystal polymerized in an aligned state as a host and an anisotropic dye arranged according to the alignment of the liquid crystal as a guest A guest-host type polarizer may be used, but is not limited thereto.

The type of polyvinyl alcohol resin or derivative thereof for forming the PVA-based polarizer is not particularly limited, and any PVA resin or derivative thereof known to be capable of forming the PVA-based polarizer can be used without particular limitation. . However, typical examples of the PVA-based resin derivative include polyvinyl formal resin or polyvinyl acetal resin. In addition, the PVA-based polarizer can be formed using PVA-based commercially available films commonly used in the manufacture of polarizers in the art, for example, P30, PE30, PE60 from Kuraray, M2000, M3000, and M6000 from Japan Synthetic Industries Co., Ltd. may be

The resin included in the PVA-based polarizer may have, for example, a polymerization degree of about 1,000 to about 10,000 or about 1,500 to about 5,000. When the degree of polymerization is within the above range, it may be advantageous to allow free molecular movement and flexibly mix with iodine or dichroic dye.

According to one embodiment of the present application, a stretched PVA film may be used as the polarizer. Transmittance or polarization degree of the polarizer may be appropriately adjusted in consideration of the purpose of the present application. For example, the transmittance of the polarizer may be 42.5% to 55%, and the degree of polarization may be 65% to 99.9997%. The transmittance and polarization may be values measured for light having a wavelength of about 550 nm.

In one example, a polarizer protective film present on one side or both sides of the polarizer may be further included. The protective film may be attached to the polarizer via an adhesive layer.

A triacetyl cellulose (TAC)-based film, a cyclic olefin-based polymer (COP) film, a cyclic olefin-based copolymer (COC) film, or an acrylic film may be used as the protective film for the polarizer. The protective film of the polarizer preferably exhibits high transparency such that the light transmittance is 85% to 100% in consideration of excellent visibility and optical characteristics of the display device.

The polarizing plate may further include a surface treatment layer. The surface treatment layer may be formed on one side of the protective film of the polarizer. Specifically, the surface treatment layer may be formed on one side of the protective film of the polarizer located on the opposite side on which the scattering adhesive layer of the polarizer is formed. Examples of the surface treatment layer include, but are not limited to, a hard coating layer, a low reflection layer, an anti-glare layer, and an anti-fingerprint layer. The surface treatment layer may be disposed on the outermost side of the polarizing plate.

The thickness of the protective film of the polarizer may be within a range of 20 μm to 100 μm. When the thickness of the protective film of the polarizer satisfies the above range, there is an effect of securing mechanical strength capable of protecting the polarizer and simultaneously securing roll process workability.

The composition or formation method of the adhesive layer for attaching the polarizer and the protective film is not particularly limited, and the adhesive layer may be formed by applying any composition that has been previously used for bonding the polarizer and the protective film. In one example, the adhesive layer may be a UV adhesive. In addition, the thickness of the adhesive layer is within the range of 0.5 μm to 4.0 μm, and good coating uniformity can be secured as the thickness of the adhesive layer satisfies this range.

The polarizing plate may further include a retardation layer between the polarizer and the scattering adhesive layer. The retardation layer may be, for example, a liquid crystal layer or an elongated polymer layer. The liquid crystal layer may include a polymerizable liquid crystal compound in a polymerized state. In the present specification, the term "polymerizable liquid crystal compound" may refer to a compound that includes a site capable of exhibiting liquid crystallinity, for example, a mesogen backbone, and includes one or more polymerizable functional groups. . The polymerizable functional group may be, for example, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group. Examples of the stretched polymer layer include polyolefin such as polyethylene or polypropylene, cycloolefin polymer (COP) such as polynorbornene, polyvinyl chloride, polyacrylonitrile, polysulfone, acrylic resin, poly Polymer layer containing polyesters such as carbonate, polyethylene terephthalate, polyacrylates, polyvinyl alcohol, or cellulose ester-based polymers such as TAC (Triacetyl cellulose) or copolymers of two or more monomers among the monomers forming the polymers can be used.

The retardation layer may have, for example, 1/4 wavelength phase delay characteristics. In this specification, the term n-wavelength phase retardation characteristic means a characteristic capable of delaying the phase of incident light by n times the wavelength of the incident light within at least a part of the wavelength range. The 1/4 wavelength phase delay characteristic may be a characteristic of converting incident linearly polarized light into elliptically polarized light or circularly polarized light, and conversely converting incident elliptically polarized light or circularly polarized light into linearly polarized light. In one example, the retardation layer may have an in-plane retardation of light having a wavelength of 550 nm within a range of 90 nm to 300 nm. In another example, the in-plane retardation may be 100 nm or more, 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, or 130 nm or more. In addition, the in-plane retardation is 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, or 145 nm or less.

The polarizing plate may further include a hard layer between the polarizer and the scattering adhesive layer. An adhesive layer may be exemplified as the hard layer. As the adhesive layer, a UV curable adhesive layer may be used. In addition, the thickness of the adhesive layer may be 0.5 μm to 4.0 μm, and good coating uniformity may be secured as the thickness of the adhesive layer satisfies this range.

1 to 3 exemplarily show the structure of the polarizing plate of the present application, respectively. As shown in FIG. 1, the polarizing plate includes a scattering adhesive layer 100, a retardation layer 200, a polarizer protective film 300, a polarizer 400, a polarizer protective film 500, and a surface treatment layer 600. can be included sequentially. Alternatively, as shown in FIG. 2, the polarizing plate may sequentially include a scattering adhesive layer 100, a polarizer protective film 300, a polarizer 400, a polarizer protective film 500, and a surface treatment layer 600. can Alternatively, as shown in FIG. 3, a scattering adhesive layer 100, a hard layer 700, a polarizer 400, a protective film 500 for the polarizer, and a surface treatment layer 600 may be sequentially included.

The polarizing plate may be provided with a release film attached to one surface of the scattering adhesive layer, and the release film may be removed when adhered to the display panel. The release film may serve to protect the scattering adhesive layer until the polarizer is attached to the display panel. The release film is a release film well known in the art, for example, an acrylic film, a polyethylene terephthalate (PET) film, a triacetyl cellulose (TAC) film, a polynorbornene (PNB) film, a cycloolefin polymer (COP) film, A polycarbonate (PC) film or the like may be used, but is not limited thereto.

This application also relates to an OLED display device. The OLED display device may include an OLED display panel and the polarizer disposed on one side of the OLED display panel. At this time, one surface of the scattering adhesive layer of the polarizing plate may be in direct contact with the OLED display panel. The polarizing plate may be disposed on a viewing side of the OLED display panel. When the polarizing plate of the present application is applied to an OLED display device, it may be advantageous to improve the problem of rainbow stains occurring in the appearance of the OLED display device, and to exhibit excellent visual sensation, excellent hardness, and excellent heat resistance and moist heat resistance.

The OLED display panel may sequentially include a substrate, a lower electrode, an organic light emitting layer, and an upper electrode. The organic emission layer may include an organic material capable of emitting light when a voltage is applied to the lower electrode and the upper electrode. One of the lower electrode and the upper electrode may be an anode and the other may be a cathode. The anode is an electrode into which holes are injected and may be made of a conductive material having a high work function, and the cathode is an electrode into which electrons are injected and may be made of a conductive material having a low work function. In general, a transparent metal oxide layer such as ITO or IZO having a high work function may be used as the anode, and a metal electrode having a low work function may be used as the cathode. Since the organic light emitting layer is generally transparent, a transparent display can be implemented when the upper and lower electrodes are transparent. In one example, when the thickness of the metal electrode is very thin, a transparent display can be implemented.

The OLED display panel may further include an encapsulation substrate functioning to prevent moisture and/or oxygen from entering from the outside on the upper electrode. An auxiliary layer may be further included between the lower electrode and the organic light emitting layer and between the upper electrode and the organic light emitting layer. The auxiliary layer may include a hole transporting layer for balancing electrons and holes, a hole injecting layer, an electron injecting layer, and an electron transporting layer. However, it is not limited thereto.

The polarizer may be disposed on a light emitting side (light emitting side) of the OLED display panel. For example, in the case of a bottom emission structure in which light is emitted toward the base substrate, it may be disposed outside the base substrate, and in the case of a top emission structure in which light is emitted toward the encapsulation substrate, it may be disposed outside the encapsulation substrate. there is. When the polarizing plate includes the retardation layer, visibility and performance of the display device can be improved by preventing external light from being reflected by a reflective layer made of metal, such as electrodes and wires of the OLED panel and coming out to the outside of the OLED panel.

This application relates to a polarizing plate and its use. The present application provides a polarizing plate capable of improving the problem of occurrence of rainbow stains on the appearance of an OLED display device, excellent visual sensation, excellent hardness, and excellent heat and moisture resistance durability, and an OLED display device including the polarizing plate.

1 exemplarily shows the structure of the polarizing plate of the present application.

2 exemplarily shows the structure of the polarizing plate of the present application.

3 exemplarily shows the structure of the polarizing plate of the present application.

Hereinafter, the present application will be specifically described through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the examples presented below.

Example 1

Acrylic polymer (LC-6BB, Soken) 100 parts by weight, curing agent (T-743L, Soken) 0.01 parts by weight, curing agent (T-706BB, Soken) 0.45 parts by weight, silane coupling agent (T-789J, Soken) 0.02 parts by weight After adding 0.29 parts by weight of antistatic agent (FC4400, 3M) and 4.0 parts by weight of beads (Tospearl 145, Momentive) to a reaction vessel, 20 parts by weight of a solvent (Ethyl acetate) was added to 100 parts by weight of acrylic polymer (LC-6BB). The pressure-sensitive adhesive composition was prepared by adding. The acrylic polymer is a polymer of 94 parts by weight of butyl acrylate (BA) and 4 parts by weight of acrylic acid (AA). The beads are spherical particles containing a silicone resin and having an average particle diameter (D50) of about 4.5 μm. The refractive index of the acrylic polymer is 1.46, and the refractive index of the bead is 1.42. The refractive index is a value measured for a light source having a wavelength of 350 nm to 1450 nm at a temperature of 25° C. using an Abbe refractometer.

After mixing the pressure-sensitive adhesive composition with a stirrer for 50 minutes, the first release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm was applied to a thickness of about 22 μm after drying, and held at 80° C. for 3 minutes. It was dried to form a scattering pressure-sensitive adhesive layer. An adhesive film was prepared by laminating a second release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm and different in peel force from the first release film on the scattering adhesive layer formed on the first release film.

A first protective film (TAC film) having a thickness of 65 μm was laminated on one side of a polarizer (iodine dyed PVA-based stretched film) having a thickness of 25 μm, and a second protective film having a thickness of 45 μm ( TAC film) was laminated. A low reflection layer having an average reflectance of about 2% for a wavelength of 380 nm to 780 nm was formed on one side of the first protective film, and the surface was treated. A 1/4 wave plate (liquid crystal layer) was formed on one side of the second protective film. After removing the second release film from the adhesive film, the scattering adhesive layer was stacked so as to be attached to the 1/4 wave plate to prepare a polarizing plate.

Example 2

A polarizing plate was prepared in the same manner as in Example 1, except that the content of the beads was changed to 2 parts by weight.

Example 3

A polarizing plate was prepared in the same manner as in Example 1, except that the content of the beads was changed to 7 parts by weight.

Example 4

Acrylic polymer (LC-6BB, Soken) 100 parts by weight, curing agent (T-743L, Soken) 0.005 parts by weight, curing agent (T-706BB, Soken) 2.02 parts by weight, silane coupling agent (T-789J, Soken) 0.10 parts by weight After putting 2.00 parts by weight of an antistatic agent (FC4400, 3M) and 4.5 parts by weight of beads (TSR, Momentive) into a reaction vessel, a solvent (Ethyl acetate) was added to prepare an adhesive composition. The acrylic polymer is a polymer of 94 parts by weight of butyl acrylate (BA) and 4 parts by weight of acrylic acid (AA). The beads include silicone resin and are spherical particles having an average particle diameter (D50) of 2.2 to 2.5 μm. The refractive index of the acrylic polymer is 1.46, and the refractive index of the bead is 1.42. The refractive index is a value measured for a light source having a wavelength of 350 nm to 1450 nm at a temperature of 25° C. using an Abbe refractometer.

After mixing the pressure-sensitive adhesive composition with a stirrer for 50 minutes, the first release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm was applied to a thickness of about 22 μm after drying, and held at 80° C. for 3 minutes. It was dried to form a scattering pressure-sensitive adhesive layer. An adhesive film was prepared by laminating a second release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm and different in peel force from the first release film on the scattering adhesive layer formed on the first release film.

A first protective film (TAC film) having a thickness of 65 μm was laminated on one side of a polarizer (iodine dyed PVA-based stretched film) having a thickness of 25 μm, and a second protective film having a thickness of 45 μm ( TAC film) was laminated. A low reflection layer having an average reflectance of about 2% for a wavelength of 380 nm to 780 nm was formed on one side of the first protective film, and the surface was treated. A 1/4 wave plate (liquid crystal layer) was formed on one side of the second protective film. After removing the second release film from the adhesive film, the scattering adhesive layer was stacked so as to be attached to the 1/4 wave plate to prepare a polarizing plate.

Example 5

A polarizing plate was prepared in the same manner as in Example 4, except that the content of the beads was changed to 6.0 parts by weight.

Example 6

A polarizing plate was prepared in the same manner as in Example 4, except that the content of the beads was changed to 7.0 parts by weight.

Example 7

In the same manner as in Example 4, except that the beads were changed to spherical particles (Tospearl 145, Momentive) having an average particle diameter (D50) of about 4.5 μm and a refractive index of 1.42, and the content of the beads was changed to 5.0 parts by weight. A polarizing plate was prepared.

Example 8

In the same manner as in Example 4, except that the beads were changed to spherical particles (Tospearl 145, Momentive) having an average particle diameter (D50) of about 4.5 μm and a refractive index of 1.42, and the content of the beads was changed to 8.0 parts by weight. A polarizing plate was prepared.

Comparative Example 1

A polarizing plate was prepared in the same manner as in Example 1, except that beads were not added.

Comparative Example 2

Acrylic polymer (AD-701, LG Chem) 100 parts by weight, curing agent (T-39, Soken) 0.04 parts by weight, silane coupling agent (T-789J, Soken) 0.06 parts by weight and antistatic agent (HQ115, 3M) 0.27 parts by weight After adding parts by weight to the reaction vessel, 20 parts by weight of a solvent (ethyl acetate) was added to 100 parts by weight of the acrylic polymer (AD-701) to prepare an adhesive composition. The acrylic polymer is a polymer of 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (4-HBA). The refractive index of acrylic polymer is 1.468. The refractive index is a value measured for a light source having a wavelength of 350 nm to 1450 nm at a temperature of 25° C. using an Abbe refractometer.

After mixing the pressure-sensitive adhesive composition with a stirrer for 50 minutes, the first release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm was applied to a thickness of about 22 μm after drying, and held at 80° C. for 3 minutes. It was dried to form a scattering pressure-sensitive adhesive layer. An adhesive film was prepared by laminating a second release film (MRP38, Mitsubishi Plastics) having a thickness of 38 μm and different in peel force from the first release film on the scattering adhesive layer formed on the first release film.

A first protective film (TAC film) having a thickness of 65 μm was laminated on one side of a polarizer (iodine dyed PVA-based stretched film) having a thickness of 25 μm, and a second protective film having a thickness of 45 μm ( TAC film) was laminated. A low reflection layer having an average reflectance of about 2% for a wavelength of 380 nm to 780 nm was formed on one side of the first protective film, and the surface was treated. A 1/4 wave plate (liquid crystal layer) was formed on one side of the second protective film. After removing the second release film from the prepared adhesive film, the scattering adhesive layer was laminated to be attached to the 1/4 wave plate to prepare a polarizing plate.

Comparative Example 3

A polarizing plate was prepared in the same manner as in Comparative Example 2, except that 4 parts by weight of beads were further added. The beads are spherical particles containing a silicone resin and having an average particle diameter (D50) of about 4.5 μm. Also, the refractive index of the bead is 1.42. The refractive index is a value measured for a light source having a wavelength of 350 nm to 1450 nm at a temperature of 25° C. using an Abbe refractometer.

Comparative Example 4

A polarizing plate was prepared in the same manner as in Example 4, except that beads were not added.

Comparative Example 5

A polarizing plate was prepared in the same manner as in Example 4, except that the beads were changed to spherical particles (Tospearl 145, Momentive) having an average particle diameter (D50) of about 4.5 μm and the content of the beads was changed to 2.0 parts by weight. The bead (Tospearl 145, Momentive) includes a silicone resin and has a refractive index of 1.42.

Comparative Example 6

A polarizing plate was prepared in the same manner as in Example 4, except that the content of the beads was changed to 1.5 parts by weight.

After measuring the storage modulus and haze for Examples 1 to 8 and Comparative Examples 1 to 6, the results are shown in Table 1.

Measurement example 1. Haze measurement

After preparing a sample by cutting the polarizing plate into a size of width × length = 5 cm × 5 cm, the haze was measured at 25 ° C using a haze meter (HM-150, Murakami color research laboratory). The haze is a value measured for light with a wavelength of 380 nm to 780 nm.

Measurement Example 2. Storage modulus measurement

After folding the scattering adhesive layer and stacking it in 16 layers, prepare a sample so that the size is width × length = 15 cm × 20 cm, and then use ARES-G2 (TA Instruments) equipment, storage modulus at 25 ° C and strain 50%. was measured, and a value of a frequency of 1 rad/sec was extracted.

	Haze (%)	Storage Modulus (Pa)
Example 1	26%	87,452
Example 2	20%	87,569
Example 3	30%	89,675
Example 4	30.0%	87569
Example 5	35.0%	89675
Example 6	40.0%	89883
Example 7	30.0%	88099
Example 8	40.0%	87305
Comparative Example 1	One%	88,293
Comparative Example 2	One%	51,230
Comparative Example 3	26%	50,284
Comparative Example 4	0.5%	88293
Comparative Example 5	11.0%	86772
Comparative Example 6	10.0%	87452

With respect to Examples 1 to 8 and Comparative Examples 1 to 6, glass sliding distance, presence or absence of staining, heat resistance reliability and moist heat resistance reliability were evaluated, and the results are shown in Table 2.

Measurement Example 3. Glass Creep Measurement

The polarizing plate was cut into a size of 10 mm x 100 mm in width x length. After peeling the first release film from the polarizing plate, the pressure-sensitive adhesive layer of the polarizing plate is applied to an area of 10 mm × 10 mm in the center of a glass plate (soda lime glass) having a width × length × thickness of 30 mm × 40 mm × 0.8 mm. A specimen was prepared by attaching it so as to come into contact with a glass plate. After degassing the specimen at 50° C. and 5 atm for 15 minutes, the pushing distance was measured. Specifically, the specimen was loaded into a texture analyzer (Stable micro system, XT plus) and the polarizer and glass plates were fixed. When the polarizing plate was pulled in one direction with a force of 800 gf for 1000 seconds, the distance (unit: μm) by which the polarizing plate was pushed away from the glass substrate was measured. In general, it is saturated within 1000 seconds (a state in which the rolling distance does not increase more and comes out uniformly), and in this experiment, the rolling distance in the final 1000 seconds was measured and listed in Table 2 below. The lower the glass slip distance, the higher the hardness of the sample.

Evaluation Example 1. Presence or absence of stain

After cutting the polarizing plate to A4 size, removing the first release film from the polarizing plate, attaching it to an OLED panel (Micro lens array OLED, LGD), operating the OLED panel, and visually observing whether stains occurred.

Evaluation Example 2. Evaluation of heat resistance reliability and moist heat resistance reliability

After cutting the polarizing plate to width × length = 160 mm × 90 mm, a sample was prepared by attaching it to an A4 size glass plate (soda lime glass) and degassing. After putting the sample into a chamber maintained under conditions of heat resistance reliability (temperature 80° C.) and moist heat resistance reliability (temperature 60° C., relative humidity 90%), the sample was maintained for 500 hours. After observing whether bubbles were generated in the sample, reliability was evaluated based on the following criteria.

◎: no bubbles

○: less than 5 bubbles

△: 5 or more bubbles

×: Occurrence of lifting of the polarizer

	Glass slip distance (μm)	Whether or not there is staining	heat resistance reliability	Moist heat resistance reliability
Example 1	212	non-occurrence	◎	◎
Example 2	210	weak occurrence	◎	◎
Example 3	224	non-occurrence	◎	◎
Example 4	210	non-occurrence	◎	◎
Example 5	224	non-occurrence	◎	◎
Example 6	209	non-occurrence	◎	◎
Example 7	220	non-occurrence	◎	◎
Example 8	216	non-occurrence	◎	◎
Comparative Example 1	209	strong occurrence	◎	◎
Comparative Example 2	434	strong occurrence	◎	◎
Comparative Example 3	455	non-occurrence	○	○
Comparative Example 4	209	generation	◎	◎
Comparative Example 5	215	generation	◎	◎
Comparative Example 6	212	generation	◎	◎

For Examples 4 to 8 and Comparative Examples 4 to 6, sparkling phenomenon and camera recognition were evaluated and evaluated, and the results are shown in Table 3.

Evaluation Example 3. Evaluation of sparkling phenomenon

After cutting the polarizing plate to A4 size, removing the first release film from the polarizing plate, attaching it to a monitor with a green background, and visually observing whether there is a sparkling (glitter) phenomenon in a darkroom environment at room temperature. The grade was evaluated according to the degree of sparkling phenomenon as follows.

Lv 0: No sparkling phenomenon

Lv 1: Weak sparkling phenomenon

Lv 2: Sparkling Phenomenon

Lv 3: During sparkling phenomenon

Lv 4: Strong sparkling phenomenon

Lv 5: Sparkling Phenomenon Strong

Evaluation Example 4. Camera Recognition Evaluation

After cutting the polarizing plate into an A4 size, an arbitrary red line was drawn on the release film surface of the polarizing plate, and the distribution of beads around the line was observed with an optical microscope (x50 magnification) as a reference. If the distribution of beads is high, attachment errors may occur because the camera recognizes the beads and incorrectly catches the reference line during the attachment process.

	degree of sparkling	camera recognition
Example 4	Lv 1	unrecognized
Example 5	Lv 1	unrecognized
Example 6	Lv 1	unrecognized
Example 7	Lv 5	recognize
Example 8	Lv 5	recognize
Comparative Example 4	Level 0	unrecognized
Comparative Example 5	Lv 4	recognize
Comparative Example 6	Lv 1	unrecognized

[Description of code]

100: scattering adhesive layer, 200: retardation layer, 300: polarizer protective film, 400: polarizer, 500: polarizer protective film, 600: surface treatment layer, 700: hard layer

Claims (12)

1. A polarizing plate comprising a polarizer and a scattering adhesive layer present on one surface of the polarizer, wherein the scattering adhesive layer has a storage modulus of 70,000 Pa or more at a temperature of 25 ° C and a frequency of 1 rad / sec, and the polarizer has a haze of 15% or more polarizer.
2. The polarizing plate according to claim 1, wherein the scattering adhesive layer comprises an adhesive resin and beads.
3. The polarizing plate according to claim 2, wherein the adhesive resin is an acrylic resin.
4. The polarizing plate according to claim 2, wherein a difference (A-B) between the refractive index (A) of the adhesive resin and the refractive index (B) of the beads is within a range of 0.04 to 0.1.
5. The polarizing plate of claim 2 , wherein the bead contains a silicone resin.
6. The polarizing plate according to claim 2, wherein the bead is included in the range of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the adhesive resin.
7. The polarizing plate according to claim 1, wherein the thickness of the scattering adhesive layer is in the range of 15 μm to 25 μm.
8. The polarizing plate of claim 1, wherein the scattering pressure-sensitive adhesive layer has a glass sliding distance measured at 800 gf for 1000 seconds in the range of 150 μm to 250 μm.
9. The polarizing plate according to claim 1, further comprising a protective film of the polarizer present on one side or both sides of the polarizer.
10. The polarizing plate according to claim 1, further comprising a retardation layer between the polarizer and the scattering adhesive layer.
11. An OLED display device comprising an organic light emitting diode (OLED) display panel and the polarizing plate of claim 1 disposed on one surface of the OLED display panel.
12. 12. The OLED display device according to claim 11, wherein the polarizer is disposed on a light emission side of the OLED display panel.

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